Effect of ceria and zirconia supports on NO reduction over platinum-group metal catalysts: A DFT study with comparative experiments

Koga, Hiroaki; Hayashi, Akihito; Ato, Yoshinori; Tada, Kohei; Hosokawa, Saburo; Tanaka, Tsunehiro; Okumura, Mitsutaka

doi:10.1016/j.cattod.2018.07.023

Cited by 25 publications

(17 citation statements)

References 44 publications

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“…Okamoto et al [11] found that Cu/ZrO 2 catalysts showed high NO conversion to N 2 at low temperature through a nitrous oxide (N 2 O) intermediate for a NO-CO reaction. As the supporter, ZrO 2 has better performance than CeO 2 in reducing the energy barrier of NO dissociation [12]. Besides, ZrO 2 also provides abundant NO x adsorption sites [13][14][15], which is beneficial for NO reduction.…”

Section: Introductionmentioning

confidence: 99%

Catalytic Reaction Mechanism of NO–CO on the ZrO2 (110) and (111) Surfaces

Cao

Zhang

Wang

et al. 2019

IJMS

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Due to the large population of vehicles, significant amounts of carbon monoxide (CO), nitrogen oxides (NOx), and unburned hydrocarbons (HC) are emitted into the atmosphere, causing serious pollution to the environment. The use of catalysis prevents the exhaust from entering the atmosphere. To better understand the catalytic mechanism, it is necessary to establish a detailed chemical reaction mechanism. In this study, the adsorption behaviors of CO and NO, the reaction of NO reduction with CO on the ZrO2 (110) and (111) surfaces was performed through periodic density functional theory (DFT) calculations. The detailed mechanism for CO2 and N2 formation mainly involved two intermediates N2O complexes and NCO species. Moreover, the existence of oxygen vacancies was crucial for NO reduction reactions. From the calculated energy, it was found that the pathway involving NCO intermediate interaction occurring on the ZrO2 (110) surface was most favorable. Gas phase N2O formation and dissociation were also considered in this study. The results indicated the role of reaction intermediates NCO and N2O in catalytic reactions, which could solve the key scientific problems and disputes existing in the current experiments.

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Section: Introductionmentioning

confidence: 99%

Catalytic Reaction Mechanism of NO–CO on the ZrO2 (110) and (111) Surfaces

Cao

Zhang

Wang

et al. 2019

IJMS

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“…ox ox red red (7) We assume that the capacity of the PGM surface is very small compared to the OSM capacity. Therefore, in contrast to the ceria reactions, no coupling between ξ and the species balance is done.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

“…Detailed microkinetic approaches aim to assist in the development of new materials or new structures, for example, the addition of NO storage components . Pore-scale simulations of a coated GPF (cGPF) analyze the washcoat deposition and the influence of the coating on the diffusion. , The kinetics of these models are usually calibrated by synthetic gas test benches with simplified inlet feeds or via density functional theory (DFT) calculations. − Because of the high computational effort and the broad parameter space, these approaches are not suitable for the simulation of transient driving cycles …”

Section: Introductionmentioning

confidence: 99%

Modeling the Catalytic Performance of Coated Gasoline Particulate Filters under Various Operating Conditions

Walter

Neumann

Hinrichsen

2021

Ind. Eng. Chem. Res.

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Coated gasoline particulate filters (cGPFs) can reduce gaseous as well as particulate emissions with the same device. However, their more complex design compared to conventional open monoliths requires accurate models in the development phase. We therefore present a new global kinetic model for cGPFs considering standard three-way catalyst reactions and extend it with the impact of lean–rich cycling, referred to as dithering. Submodels are introduced for the oxygen storage and for the extent of oxidation of the active centers. Therefore, the model captures the enhanced conversion of the catalyst under various dithering as well as steady-state conditions. Several steady-state and transient experiments were conducted on a specially equipped dynamic engine test bench in order to calibrate the approach. The proposed model accurately predicts the tailpipe emissions released in a worldwide harmonized light vehicles test procedure driving cycle that is not part of the original calibration data.

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“…Suzuki et al developed multiscale theoretical methods for predicting the sintering behavior of Pt on various catalyst supports [9]. On the microscale, density functional theory (DFT) 2 of 16 calculations are commonly applied, and reported examples include Pt, Pd, and Rh particles on CeO 2 , ZrO 2 , and CZ [10,11]. In these calculations, the PGM-support interaction energy is estimated and used to discuss the PGM sintering.…”

Section: Introductionmentioning

confidence: 99%

In Situ TEM Study of Rh Particle Sintering for Three-Way Catalysts in High Temperatures

Nakayama

Nagata²,

Abe

et al. 2020

Catalysts

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One of the main factors in the deterioration of automobile three-way catalysts is the sintering of platinum group metals (PGMs). In this study, we used in situ tunneling electron microscopy (TEM) to examine the sintering of Rh particles as the temperature increases. Two types of environmental conditions were tested, namely, vacuum atmosphere with heating up to 1050 °C, and N2 with/without 1% O2 at 1 atm and up to 1000 °C. Under vacuum, Rh particles appeared to be immersed in ZrO2. In contrast, at 1 atm N2 with or without 1% O2, the sintered Rh particles appeared spherical and not immersed in ZrO2. The latter trend of Rh sintering resembles the actual engine-aged catalyst observed ex situ in this study. In the N2 atmosphere, the sintering of support material (ZrO2 or Y-ZrO2) was first observed by in situ TEM, followed by Rh particle sintering. The Rh particle size was slightly smaller on Y-ZrO2 compared to that on ZrO2. To better understand these experimental results, density functional theory was used to calculate the systems’ junction energies, assuming three layers of Rh(111) 4 × 4 structures joined to the support material (ZrO2 and Y-ZrO2). The calculated energies were consistent with the in situ TEM observations in the N2 atmosphere.

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Effect of ceria and zirconia supports on NO reduction over platinum-group metal catalysts: A DFT study with comparative experiments

Cited by 25 publications

References 44 publications

Catalytic Reaction Mechanism of NO–CO on the ZrO2 (110) and (111) Surfaces

Catalytic Reaction Mechanism of NO–CO on the ZrO2 (110) and (111) Surfaces

Modeling the Catalytic Performance of Coated Gasoline Particulate Filters under Various Operating Conditions

In Situ TEM Study of Rh Particle Sintering for Three-Way Catalysts in High Temperatures

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